This section provides background information related to the present disclosure which is not necessarily prior art.
Photovoltaic modules, devices, or cells, can include multiple layers (or coatings) created on a substrate (or superstrate). For example, a photovoltaic device can include a barrier or window layer, a transparent conductive oxide layer, a buffer layer, and a semiconductor layer formed in a stack on a substrate. Each layer may in turn include more than one layer or film. For example, a semiconductor window layer and a semiconductor absorber layer together can be considered a semiconductor layer. Additionally, each layer can cover all or a portion of the device and/or all or a portion of a layer or a substrate underlying the layer. For example, a “layer” can include any amount of any material that contacts all or a portion of a surface.
A glass layer is typically the top or outer-most layer in a single-junction photovoltaic cell of a photovoltaic (PV) device and is formed from a high band gap material to allow transmittance of sunlight to underlying layers of the device. The glass layer is exposed to atmosphere and can become coated with dust, dirt, sand, and the like during use, collectively referred to hereinafter as “dust”. As dust develops and thickens, transmittance of sunlight through the glass layer to underlying layers is diminished, reducing the efficiency of the PV device. Methods to clean PV device glass layers have therefore been developed that include water washing systems, powered, and robotic cleaning systems. Such systems have substantial hardware costs, require additional power to operate, and if water is used require a substantial source of water. Alternate, less power intensive systems and systems that do not require water as a cleaning agent are therefore desirable.